Drawing instrument



April 16, 1963 R. c. TUCKER 3,035,344

DRAWING INSTRUMENT Filed Nov. 27, 1 959 3 Sheets-Sheet 1 40 FIG.1

INVENTOR. Richard C. Tucker AT TO RNEY April 19-63 R. c. TUCKER 3,085,344

DRAWING INSTRUMENT Filed Nov. 27, 1959 5 Sheets-Sheet 2 465 45c 46D 1a FIG.8

A I T I 3o INVENTOR.

FIG.4 Richard C. Tucker ATTORNEY April 16, 1953 R. c. TUCKER 3,085,344

DRAWING INSTRUMENT Filed Nov. 27, 1959 3 Sheets-Sheet 3 FIG. 10 H may 52 INVENTOR. Richard C. Tucker ATTORNEY United States Patent 3,085,344 DRAWING INSTRUMENT Richard C. Tucker, Darien, Qonm, assignor, by mesne assignments, to Pennywise Investment Association, North Ridge, Claymont, Del, a corporation of Delaware Filed Nov. 27, 1959, Ser. No. 855,793 3 Claims. (Cl. 33--80) The present invention relates to a drawing instrument and more particularly to a drawing instrument, for use with sketch pads of different widths, which combines in a single compact unit the features of a T square and angles.

There are many instances where sketches have to be drawn without any equipment available for making them other than a straight edge and a sketch pad. The sketches as a result ar usually inaccurate and difiicult to draw.

It is the object of this invention to provide a simple, compact drawing instrument capable of being carried about in a brief case or letter size portfolio which can be used with a sketch pad to make fast, neat, accurate sketches.

Therefore, the drawing instrument in this invention comprises a transverse member adapted to lie across a sketch pad. End members are attached to the ends of the transverse member to square the drawing instrument against the sketch pad with the longitudinal edges of the transverse member providing a pair of straight edges. vAn angle arm also having a pair of straight edges is pivotally attached to the transverse member and extends angularly therefrom so that a number of predetermined angles can be drawn with the straight edge of the transverse member.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descrip tive matter in which I have illustrated and described a preferred form of my invention.

In the drawings:

FIG. 1 is a perspective of a drawing instrument, em bodying the construction of the present invention, shown positioned on a sketch pad;

FIG. 2 is a plan view of the drawing instrument, with a portion of both the transverse member and the angle member removed;

FIG. 3 is a bottom plan view of the transverse mem ber with a portion thereof removed;

FIG. 4 is a longitudinal sectional view of the transverse member .taken along the line 44 of FIG. 3 with a portion of the transverse member removed and showing the thickness in exaggerated scale;

FIG. 5 is a top plan view of the end member;

FIG. 6 is a side View taken along the line 6-6 of FIG. 2 showing the end member in elevation and the transverse member in section and with their thicknesses shown in exaggerated scale;

FIG. 7 is a bottom plan view of the angle arm;

FIG. 8 is a longitudinal sectional view of the angle arm taken along the line 8-8 in FIG. 7 and showing the thickness of the angle arm in exaggerated scale; and

FIG. 9 is a top plan View of the angle arm;

FIG. 10 is a top plan view of another embodiment of the invention showing only a portion of the transverse member and the angle arm;

FIG. 11 is an enlarged side view taken along the line 11-41 in FIG. 10 with a portion of the angle arm broken away;

3,d85,344 Patented Apr. 16, 1963 FIG. 12 is a top plan view of the slide member;

FIG. 13 is a side elevation view of the slide member;

FIG. 14 is an enlarged end elevation view of the slide member; and

FIG. 15 is a bottom plan view of a portion of the angle arm.

In FIG. 1, a drawing instrument It) is shown positioned on a sketch pad 11. The drawing instrument is made up of a thin elongated transverse member 12, a pair of end members 14- contacting the sides of the sketch pad and attached to the transverse member by pins 16 and an angle arm 18 pivotally attached to the transverse member by a pin 20.

In position on the sketch pad, the transverse member 12 lies across the width of the pad 1 1 so that both of its ends 24- extend beyond the sides of the pad. The longitudinal edges of the transverse member provide a pair of parallel straight edges 26 disposed at right angles to the side of the sketch pad.

In the lower face of the transverse member 12 and ext-ending across its length, there is a longitudinal groove 28, see FIG. 3. The longitudinal groove 28 is rectangular in cross-section and has a depth of roughly half the thickness of the transverse member. It is centered on and extends along the longitudinal centerline of the transverse member.

In addition to the longitudinal groove, a pair of athwart grooves 3b are also formed in the lower face. The athwart grooves 3t) extend across the width of the transverse member perpendicular to the longitudinal groove and are similar in cross-sectional shape to the longitudinal groove having the same width but only about half the depth. The athwart grooves are spaced apart from one another being located close to the opposite ends 24 of the transverse member.

A narrow through-slot 32 extends along the longitudinal centerline of the transverse member forming an opening between the upper face and the longitudinal groove. The width of the through-slot 32 is considerably less than that of the longitudinal groove. As can be seen in FIG. 1, when the drawing instrument 10 is placed on the sketch pad 11, the through-slot 32 extends beyond the sides of the sketch pad and terminates at each end at a point between the end of the transverse member and the adiacent athwart groove 30.

The transverse member is formed of a transparent plastic material. Scales, which can be read by looking through the transverse member, are marked in the lower faces along both of the straight edges 26. The position of these scales on the lower face avoids any interference which would occur if a raised scale on the upper face were used.

In FIG. 2, the end members 14 are shown attached to the transverse member 12 so that their upper faces contact the lower face of the transverse member. Each end member has a squaring edge 34 arranged in opposed parallel relationship to the other and disposed perpendicularly to the straight edges 26 of the transverse member. The squaring edges 34 extend beyond the straight edges 26 of the transverse member 12 in a T-shaped arrangement. With any normal variations in the width of individual sketch pads, the length or bearing surface of the squaring edges 34- is sufficient to provide accuracy in drawing lines with the straight edges 26. As an example, in a drawing instrument for use with a sketch pad 8.5 inches wide, the transverse member would be 1.375 inches in width and the length of the squaring edges of the end member would be three (3) inches. The width of the end member taken normal to the squaring edge is less than that of the transverse member, or in the example just cited it would be one (1) inch.

A tongue 36 of rectangular cross section protrudes upwardly from and extends across the upper face of each of the end members at right angles to the squaring edge. The tongue 36 is slightly smaller in width than the longitudinal groove 28 so that it will be engagably fitted therein. In the example of the drawing instrument cited above, the longitudinal groove would be .375 inch wide while the tongue would be .371 inch wide thereby providing a tight fit so that the transverse member will not tend to shift position on the sketch pad.

IN FIG. 6, the end member 14 is illustrated having its tongue 36 engaged within the longitudinal groove 28 of the transverse member 12. A. pin hole 38 is located on the longitudinal centerline of the tongue 36 midway between its ends and passes through the end member. The lower end 38A of the pin hole has an increased diameter to provide a recess to receive a spring 3%. The pin 16 with the spring 39 coiled about and attached to its lower end passes through the pin hole in the end member and the through-slot 32 in the transverse member to attach these members together. A knob 49 is provided on top of the pin and bears against the transverse member. As shown in PEG. 6, the pin is spring loaded to hold the end member in position against the transverse member. However, this is only one of several ways in which these two members can be held together, another would be to have the upper end of the pin threaded and the knob 49 screwed thereon.

By sliding the knobs 40, the pins 16 will side along the through-slot 32 and the end members 14- can be positioned along the transverse member 12 to adjust to the width of the sketch pad 11. The squaring edges 34 bear against the sides of the pad so that the drawing instrument it can be moved either up or down the pad while the straight edges 26 are maintained normal to the sides of the pad.

The angle arm 18 is a thin elongated member made of transparent plastic smaller both in width and length than the transverse member. The longitudinal edges of the angle arm form a pair of straight edges 42 arranged in parallel relation with one another. In its assembled working position, on the drawing instrument, the angle arm extends angularly from the transverse member and has its lower face in contact with the upper face of the transverse member. It is pivotally attached to the trans verse member by the pin 2t? having a knob 43 which is similar in construction and operation to the pins 16. A pin hole 44 is formed through the angle arm midway between its straight edges 42 and close to one end. The pin extends upwardly through the through-slot 32 in the transverse member and then through the pin hole 44 in the angle arm. The pin 2% can be moved longitudinally along the through-slot 32 thereby permitting the angle arm to be positioned across the length of the transverse member between the end members.

The portion of the angle arm 1e which extends angularly from the transverse member is beveled along its straight edges 42 and has scales marked thereon. The transverse member is not beveled on its upper face so that the angle arm is supported across its width.

In FIGS. 7 and 8, a group of four angle selector grooves 46A, 46B, 46C, 461) are shown in the lower face of the angle arm 14; arranged in nested stepped relationship. The angle selector grooves 46A, 46B, 46C, asp extend across the width of the angle arm and are symmetrically arranged about a transverse line passing through the center of the pin hole 44 and disposed perpendicularly to the straight edges 4-2. In addition they are symmetrically arranged about the longitudinal centerline of the angle arm.

The grooves 46A, 56B, 46C, 46D are nested within one another with each groove having both a difierent width and depth than its companions. Because of their variations in width and depth and their symmetrical arrangeextending relationship. As with the end members,

ment about the transverse line, the grooves provide a stepped appearance.

The deepest angle selector groove 46A has the narrowest width and is the only groove which has its sides in parallel relationship for their entire length. The remaining angle selector grooves 46B, 46C, 46D working outwardly from the deepest grooves are successively shallower and wider. Unlike the deepest groove 46A, these three grooves are not of uniform width. They are narrowest at the intersection of their sides with the longitudinal centerline of the angle arm 18 and on either side thereof, they are in diverging relationship. While the opposing sections of the sides of the grooves are diverging from each other, the diagonally opposite sections, that is the sections on opposite sides both of the transverse line and the longitudinal centerline are in parallel relationship. Though each of the grooves is of a difierent width when measured along a line parallel to the longitudinal centerline of the angle arm, they are of equal width when measured normal to the sections of their sides which are arranged in parallel relationship.

As can be noted in FTG. 2, the angle selector grooves 46A, 46B, 46C, 46D are adapted to engage with the transverse member and position the angle arm in a number of predetermined angles. In FIG. 2, the angle selector groove 46C in engageably fitted over the transverse memher to form a 45 degree and a 135 degrees angle between the straight edges of the angle arm and of the transverse member. The angle selector grooves are so arranged that the sections of their sides which are in parallel relationship will fit closely over the transverse member.

For purposes of illustrating the relative widths of the transverse member and the angle selector grooves if the example of the drawing instrument mentioned earlier is used, the transverse member is 1.375 inches wide while the parallel sides of the grooves are spaced 1.377 inches apart. This narrow clearance permits the angle arm to slide along the transverse member and at the same time to hold it securely in place for drawing purposes.

Several of the various predetermined angles which can be formed between the respective straight edges of the angle arm and transver-ses member are shown in phantom lines in FIG. 2. The deepest angle selector groove 46A permits the positioning of the angle arm at right angles to the transverse member. By rotating the angle arm about pin 20, a 60 degree angle with the horizontal can be formed by engaging the angle selector groove 468 with the transverse member and similarly 45 degree and 30 degree angles can be formed using the angle selector grooves 46C, 46D respectively.

When not in use, the drawing instrument can be foldably arranged into a compact unit for ease in storing or carrying. The end members 14 can be rotated degrees about the connecting pin 16 and the tongue on the upper faces of each will then fit into one of the athwart grooves 38 with the squaring edges 34 lying in parallel arrangement with the straight edges 26. Since the width of the end members is less than that of the transverse member when they are in this rotated position, they will not extend beyond the sides of the transverse member.

While the end members are positioned in contact with the lower face of the transverse member, the angle arm 18 contacts the upper face of the transverse member and is also rotatable about the connecting pin it so that the longitudinal centerline of each can be positioned in cothe angle arm is not as Wide as the transverse member so that it does not extend beyond the sides of the transverse member. Therefore, when not in use, both the end members and the angle arm can be foldably arranged on the transverse member to provide a simple compact unit.

In FIG. 10, another embodiment of the invention is illustrated by which the angle arm can be positioned with relation to the transverse member. The portions of this embodiment not shown are the same as set forth in FIGS.

1 9. For purposes of identifying the elements of the embodiment shown in FIGS. -15, the same reference numerals as used in FIGS. 1-9 will again be used with the addition of a prefix 1.

A longitudinal groove 128 is formed across the length of the transverse member 112. Within this groove 128 and extending along its length in parallel relationship is a pair of narrow channels 128A [formed to provide a track-like arrangement. Extending between the groove and the upper face of the transverse member is a narrow through-slot 132 similar in length to that shown in FIG. 2.

A slide member 150 is positioned within the longitudinal groove 128 and the narrow through-slot 132. A pair of upwardly extending fingers 152 run longitudinally along the slide member 150 and fit into the narrow channels 128A. This slide member 150 is held in tightly fitting sliding relationship with the transverse member so that it may be moved along the length of the through-slot 132. The pair of fingers 152 act as guides in the track-like arrangement provided by the channels 128A.

On top of and integral with the slide member a pair of upwardly projecting, straight sided protuberances 154 are formed. The long dimension of these protuberances is' in alignment with the length of the transverse member. As illustrated in FIG. 11, the protuberances 154 extend above the top of the slide member which is flush with the upper face of the transverse member. A hole 1516 extending through the slide member is arranged on its longitudinal centerline between the protuberances. The lower portion of this hole is countersunk.

The angle arm 118 is similar in general arrangement to the showing in FIG. 2, however, the means for positioning the angle arm with relation to the transverse member is different.

A knob 158 is arranged on top of the angle arm. This knob can be either formed with the angle arm or integrally attached to it. A circular opening '160 is formed through the knob and the angle arm, with the portion of the opening within the knob having a greater diameter than that in the single arm.

To attach the angle arm to the transverse member, a rivet 162 extends downwardly through the opening 160 and fits tightly over a pin 164 extending upwardly through hole 156 in the slide member. The pin 164 is held in place by its head which seats within the countersunk portion of the hole 156. The head of the rivet 162 just fits within the opening 160 flush with the top of the knob. A spring 166 is positioned about the pin and rivet within the larger diameter portion of the opening 160 to hold the angle arm in position against the transverse member. At its upper end, the spring bears against the rivet and at its lower end it is seated within an annular groove.

A number of diametrically opposed pairs of straight sided, groove-like recesses 168A, B, C, D, E arranged in a circle are formed in the lower face of the angle arm. These recesses are formed to matchingly fit the straight sided protuberances on the slide member and are adapted to seat over them in tightly fitting relationship. The angle arm can be positioned with relation to the transverse member by engaging the protuberances within a pair of the recesses.

If the protuberances are engaged by the pair of recesses 168A, the angle arm will be held in position at right angles to the transverse member. In counterclockwise order, as shown in FIG. 15, recesses 168A, B, C will position the angle arm at angles of 60, 4S and 30 degrees respectively with the transverse member. When the protuberances are engaged within recesses 168E, the angle arm will lie along the transverse member in axial alignment therewith.

For purposes of this invention, the protuberances 154 on the slide member could also be formed on the transverse member. In such an arrangement, the slide memher would not be required and the groove-like recesses of the angle arm would fit over the protuberances on the transverse member.

In both of the embodiments described herein, the angle arm is positioned with relation to the transverse member by means of straight sided grooves or groove-like recesses in the angle arm matchingly fitting over the straight edges of the transverse member or the straight sided protuberances of the slide member. These straight sided interlocking elements are of prime importance in accurately positioning the angle arm with relation to the transverse member. The tolerances normally resulting from forming the interlocking elements or from normal wear during use do not afiect the accurate angular positioning of the angle arm. The straight sided relationship of the interlocking elements avoids the looseness and relative slipping which results where round interlocking elements are used.

In view of the drawings and the description, it can readily be seen that the drawing instrument :10 provides an efficient, accurate and easy to use drafting or sketching tool in a simple, compact unit. Since the end members are movably positionable along the transverse member, they will fit sketch pads within a range odf widths. Primarily, the drawing instrument is adapted for use with sketch pads that are of sizes that can be easily carried in a letter-size folder or briefcase such as 8 /2" x 11" or 8" x 13" pads.

The squaring edges 34 of the end members 14 permit the drawing instrument to be moved up or down the pad while maintaining the straight edges of the transverse member perpendicular to the side of the pad. The squaring edge extends a suflicient distance on either side of the end member to provide both stability and accuracy considering any normal variation in pad widths. Since the end members fit closely to each side of the pad, parallel lines may be drawn with the straight edge of the transverse member without either holding the instrument or exerting lateral pressure against one of the end members.

While the transverse member permits the drawing of parallel lines across the sketch pad, lines either normal to or at a number of predetermined angles to these parallel lines can be drawn With the angle arm. In addition, since the angle arm is movably positionable across the transverse member it is also possible to draw parallel lines with the angle arm.

In this description, the transverse member and angle arm have been identified as being made of transparent plastic material, while this is a preferred material the drawing instrument could as effectively be made of a meltal or other durable, though non-transparent, materia While this drawing instrument has been shown and described in combination with a sketch pad, it could also be used with a drawing board either of a size comparable With the sketch pads we have mentioned or larger. Additionally, the transverse member and angle arm could lge used as a drawing instrument without the end memers.

It will also be understood that the number of predetermined angles which can be drawn are not limited to the number shown herein but may be either increased or decreased.

While in accordance with the provisions of the statutes, I have illustrated and described herein a specific form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

1. A drawing instrument comprising an elongated transverse member having at least one longitudinally extending straight edge, an angle arm having at least one longitudinally extending straight edge, pin connecting means pivotally attaching said angle arm to said transverse member whereby said angle arm is movably positionably longitudinally along said transverse member, and spring means in combination with said pin connecting means urging said angle arm into interlocking engagement with said transverse member, said spring means also arranged to urge said angle arm and transverse member into frictional engagement and thus hold the long tudinal position of said angle arm in said transverse member whereby said angle arm is positionable in interlocking engagement relative to said transverse memere in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles therewith.

2. A drawing instrument comprising an elongated transverse member having at least one longitudinally extending straight edge, an angle arm having at least one longitudinally extending straight edge, said angle arm having a number of straight sided grooves therein, pin connecting means pivotally attaching said angle arm to said transverse member whereby said angle arm is movably positionable along said transverse member, and spring means in combination with said pin connecting means urging the grooves in said angle arm into interlocking engagement with said transverse member, said spring means also arranged to urge said angle arm and transverse member into frictional engagement and thus hold the longitudinal position of said angle arm in said transverse member whereby said angle arm is positionable in interlocking engagement relative to said transverse member in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles therewith.

3. A drawing instrument comprising an elongated transverse member having at least one longitudinally extending straight edge, said transverse member having a longitudinal groove therein, a pair of end members engageable with said transverse member within the longitudinal groove thereof and movably positionable therealong, connecting means attaching said end members to said transverse member, each of said end members having a squaring edge arranged in opposed spaced parallel relationship with the other and disposed at right angles to the straight edge of said transverse member, an angle arm having at least one longitudinally extending straight edge and also having a number of straight sided grooves therein, pin connecting means pivotally attaching said angle arm to said transverse member whereby said angle arm is movably positionable along said transverse member, and spring means in combination with said pin connecting means urging the grooves in said angle arm into interlocking engagement with said transverse member, whereby said angle arm is positionable in interlocking engagement relative to said transverse member in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles therewith.

4. A drawing instrument comprising an elongated transverse member having at least one longitudinally extending straight edge, said transverse member having a longitudinally extending groove therein, a slide member situated within and movable along the groove of said transverse member, an angle arm having at least one longitudinally extending straight edge and also having .a number of straight sided grooves therein, pin connecting means pivotally attaching said angle arm to said slide member whereby said angle arm is movably positionable along said transverse member, and spring means in combina-tion with said pin connecting means urging the grooves in said angle arm into interlocking engagement with said slide member, said spring means also arranged to urge said angle arm and transverse member into frict3 tional engagement and thus hold the longitudinal position of said angle arm in saidtransverse member whereby said angle arm is positionable in interlocking engagement relative to said transverse member in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles therewith.

5. A drawing instrument comprising an elongated transverse member having at least one longitudinally extending straight edge and also having a longitudinal groove located therein and extending therealong, a slide member engageable with said transverse member within the groove therein in tightly fitting relationship and having a protuberance extending upwardly therefrom, a pair of end members engageable with said transverse member within its groove and movably positionable therealong, connecting means to attach said end members to said transverse member, each of said end-members having a squaring edge arranged in opposed spaced parallel relationship with the other and disposed at right angles to the straight edge of said transverse member, an angle arm having at least one longitudinally extending straight edge and also having a number of straight sided grooves therein, pin connecting means pivotally attaching said angle arm to saidslide member whereby said angle arm is movably positionable along said transverse member, and spring means in combination with said pin connecting means urging the grooves in said angle arm into interlocking engagement with the protuberance of said slide member, whereby said angle arm is positionable in interlocking engagement relative to said transverse member in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles there with. v

6. A drawing instrument comprising an elongated transverse member having an upper and a lower face, said transverse member having a pair of longitudinally extending straight edges arranged in parallel relationship, longitudinally extending straight edges arranged in parallel relationship, a longitudinally extending groove of rectangular cross-section disposed in the lower face thereof and a corresponding narrow longitudinally extending through slot positioned along the longitudinal centerline of the groove and communicating between the upper face of said transverse vessel and the groove, a pair of end members each having an upper face a lower face and a squaring edge, Walls upwardly extending from the upper face of each of said end members forming a tongue disposed normally to the squaring edge thereof, the tongue on said end members having a cross-sectional shape similar to said longituidnal groove and engageable therein, the squaring edge of each of said end members arranged in normal operating position in opposed spaced parallel relationship at right angles to the squaring edges of said transverse member, first connecting means extending through said through-slot attaching said end members to said transverse ember whereby the end members are movably positionable along said transverse member and rotatable about said first connecting means, an angle arm having an upper face a lower face a number of angle selector grooves in the lower face and a pair of parallel longitudinally extending straight edges, second connecting means extending through the through-slot of said transverse member pivotally attaching said angle arm to the upper face of said transverse member, and spring means in combination with said second connecting means urging the grooves in the lower face of said angle arm into interlocking engagement relative to said transverse member in a plurality of predetermined circumferentially spaced positions forming a number of different selected angles therewith.

7. A drawing instrument for use with a sketch pad comprising a thin transverse member of sufiicient length when positioned on the sketch pad to extend beyond the sides thereof, said transverse member having at least one longitudinally extending straight edge to be positioned perpendicularly to the sides of the pad, a pair of end members each having a squaring edge arranged in opposed parallel relationship and adapted to bear against the sides of the pad in closely fitting relationship, said end members engageably attached to and movably positionable along said transverse member to fit sketch pads of varying width, an angle arm having at least one longitudinal extending straight edge, pin connecting means pivotally attaching said angle arm to said transverse member, said angle arm having a number of straight sided grooves formed therein, and spring means in combination with said pin connecting means urging the grooves in said angle arm into interlocking engagement relative to said transverse member in a plurality of predetermined circuimferentially spaced positions forming a number of different selected angles therewith,

8. A drawing instrument for use with a sketch pad and arranged to provide a compact unit for ease in carrying and storing comprising a thin transverse member positioned across the sketch pad and having each of its ends extending beyond the sides of the pad, said transverse member having a pair of straight edges arranged in parallel relationship and disposed normally to the sides of the pad, said transverse member having a longitudinally extending groove situated along said transverse member in parallel relationship with the straight edges thereof and a pair of longitudinally extending channels formed in the groove acting as a track, said transverse member also having a pair of spaced ath-wart grooves extending across the width of said transverse member at right angles to said longitudinal groove and a through-slot smaller in Width than the groove and co-extensive and communicating therewith, a slide member arranged to slide on said track said transverse member whereby said slide member is engageable with said transverse member in tightly fitting sliding relationship, walls forming a pair of protuberances extending upwardly from said slide member to a point above said transverse member, a pair of end members each having a squaring edge arranged in opposed spaced parallel relationship with the other and adapted to bear against the side of the pad in closely fitting relationship, upwardly extending Walls forming a tongue extending across each of said end members and arranged perpendicularly to the squaring edges thereof, first pin connecting means pivotally attaching said end members to said transverse member with the tongues of the end member engageable within the groove of said transverse member whereby the end members are movably positionable across and rotatable about said transverse member so that the tongues of said end members are also engageable Within the athwart grooves of said transverse memher, an angle arm having a pair of longitudinally extending straight edges in parallel relationship, second pin connecting means pivotally attaching said angle arm to said transverse member, said angle arm having circumferentially spaced diametrically opposed pairs of straight sided grooves formed therein, and spring means in combination with said second pin connecting means selective ly urging individual pairs of the grooves in said angle arm into interlocking engagement with the protuberances on said slide member to locate the angle arm in a plurality of circumferentially spaced positions with relation to the transverse member to form therewith a number of different selected angles therewith, one or" the pairs of grooves in said angle arm arranged to locate the angle arm in longitudinal alignment with the transverse member.

References Cited in the file of this patent UNITED STATES PATENTS 429,203 Sajous June 3, 1890 814,789 Machintosh Mar. 13, 1906 1,172,631 Prout Feb. 22, 1916 2,871,567 Casten Feb. 3, 1959 FOREIGN PATENTS 366,311 Great Britain Feb. 4, 1932 

3. A DRAWING INSTRUMENT COMPRISING AN ELONGATED TRANSVERSE MEMBER HAVING AT LEAST ONE LONGITUDINALLY EXTENDING STRAIGHT EDGE, SAID TRANSVERSE MEMBER HAVING A LONGITUDINAL GROOVE THEREIN, A PAIR OF END MEMBERS ENGAGEABLE WITH SAID TRANSVERSE MEMBER WITHIN THE LONGITUDINAL GROOVE THEREOF AND MOVABLY POSITIONABLE THEREALONG, CONNECTING MEANS ATTACHING SAID END MEMBERS TO SAID TRANSVERSE MEMBER, EACH OF SAID END MEMBERS HAVING A SQUARING EDGE ARRANGED IN OPPOSED SPACED PARALLEL RELATIONSHIP WITH THE OTHER AND DISPOSED AT RIGHT ANGLES TO THE STRAIGHT EDGE OF SAID TRANSVERSE MEMBER, AN ANGLE ARM HAVING AT LEAST ONE LONGITUDINALLY EXTENDING STRAIGHT EDGE AND ALSO HAVING A NUMBER OF STRAIGHT SIDED GROOVES THEREIN, PIN CONNECTING MEANS PIVOTALLY ATTACHING SAID ANGLE ARM TO SAID TRANSVERSE MEMBER WHEREBY SAID ANGLE ARM IS MOVABLY POSITIONABLE ALONG SAID TRANSVERSE MEMBER, AND SPRING MEANS IN COMBINATION WITH SAID PIN CONNECTING MEANS URGING THE GROOVES IN SAID ANGLE ARM INTO INTERLOCKING ENGAGEMENT WITH SAID TRANSVERSE MEMBER, WHEREBY SAID ANGLE ARM IS POSITIONABLE IN INTERLOCKING ENGAGEMENT RELATIVE TO SAID TRANSVERSE MEMBER IN A PLURALITY OF PREDETERMINED CIRCUMFERENTIALLY SPACED POSITIONS FORMING A NUMBER OF DIFFERENT SELECTED ANGLES THEREWITH. 